In hierarchical storage technology, multiple types of storage devices of a storage apparatus are divided into tiers in accordance with performance. In hierarchical storage technology, the storage destination of data from a logical volume is changed to an appropriate tier based on the I/O (Input/Output) load with respect to this data. A tier change can be carried out either manually or automatically. When using hierarchical storage technology, storage devices having the performance required for data can be allocated with respect to this data only in the quantity that is needed. Therefore, the utilization efficiency of the storage apparatus can be improved.
Patent Literature 1 discloses a hierarchical storage technology, which can measure the I/O load for each piece of data included in a single file, and change the storage destination of the data in units of one file.
Patent Literature 2 discloses hierarchical storage technology, which can measure the I/O load for each piece of data included in a virtual storage area called a page, and change the storage destination of the data in units of one page.